France on Sunday called on its citizens in Lebanon to leave the country "as soon as possible" amid fears of all-out war between Israel and Hezbollah and a broader regional conflict.

"In a highly volatile security context, we once again call the attention of French nationals, particularly those passing through, to the fact that direct commercial flights and ones with stopovers to France are still available, and we invite them to make their arrangements now to leave Lebanon as soon as possible," the foreign ministry said in its travel advice notice for Lebanon.

With its call, Paris is following the example of Washington and London, which had recommended their own nationals to leave from Saturday.

France estimates that some 23,000 of its citizens live in Lebanon, and last month around 10,000 French citizens were visiting to the country.

Sweden also announced the closure of its embassy in Beirut and called on its nationals to leave.

On Thursday, the French foreign ministry had updated an information sheet by highlighting the continued availability of commercial flights to France while stopping short of calling on nationals to leave Lebanon.

On Sunday, the ministry stressed French nationals were being "urgently asked" not to travel to Lebanon as fears of a regional conflagration after Iran and its allies threatened to respond to the assassination of Hamas's political leader, blamed on Israel.

Tehran, along with Hamas and Lebanese-based, Iranian-backed ally Hezbollah, accused Israel of Wednesday killing Ismail Haniyeh.

Haniyeh was killed a day after a strike claimed by Israel killed Hezbollah military chief Fouad Chokr near Beirut.

Hezbollah said Saturday it had launched dozens of Katyusha rockets at Israel, saying the attack was in response to Israeli attacks on Lebanon.

Israeli Prime Minister Benjamin Netanyahu says his country is at "a very high level" of preparedness for any scenario -- "defensive and offensive."